Humans are thought to possess a unique proclivity to share with others – including strangers. This puzzling phenomenon has led many to suggest that sharing with strangers originates from human-unique language, social norms, warfare and/or cooperative breeding. However, bonobos, our closest living relative, are highly tolerant and, in the wild, are capable of having affiliative interactions with strangers. In four experiments, we therefore examined whether bonobos will voluntarily donate food to strangers. We show that bonobos will forego their own food for the benefit of interacting with a stranger. Their prosociality is in part driven by unselfish motivation, because bonobos will even help strangers acquire out-of-reach food when no desirable social interaction is possible. However, this prosociality has its limitations because bonobos will not donate food in their possession when a social interaction is not possible. These results indicate that other-regarding preferences toward strangers are not uniquely human. Moreover, language, social norms, warfare and cooperative breeding are unnecessary for the evolution of xenophilic sharing. Instead, we propose that prosociality toward strangers initially evolves due to selection for social tolerance, allowing the expansion of individual social networks. Human social norms and language may subsequently extend this ape-like social preference to the most costly contexts.

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Bonobos Share with Strangers

Primates occur in 90 countries, but four-Brazil, Madagascar, Indonesia, and the Democratic Republic of the Congo (DRC)-harbor 65% of the world's primate species (439) and 60% of these primates are Threatened, Endangered, or Critically Endangered (IUCN Red List of Threatened Species 2017-3). Considering their importance for global primate conservation, we examine the anthropogenic pressures each country is facing that place their primate populations at risk. Habitat loss and fragmentation are main threats to primates in Brazil, Madagascar, and Indonesia. However, in DRC hunting for the commercial bushmeat trade is the primary threat. Encroachment on primate habitats driven by local and global market demands for food and non-food commodities hunting, illegal trade, the proliferation of invasive species, and human and domestic-animal borne infectious diseases cause habitat loss, population declines, and extirpation. Modeling agricultural expansion in the 21st century for the four countries under a worst-case-scenario, showed a primate range contraction of 78% for Brazil, 72% for Indonesia, 62% for Madagascar, and 32% for DRC. These pressures unfold in the context of expanding human populations with low levels of development. Weak governance across these four countries may limit effective primate conservation planning. We examine landscape and local approaches to effective primate conservation policies and assess the distribution of protected areas and primates in each country. Primates in Brazil and Madagascar have 38% of their range inside protected areas, 17% in Indonesia and 14% in DRC, suggesting that the great majority of primate populations remain vulnerable. We list the key challenges faced by the four countries to avert primate extinctions now and in the future. In the short term, effective law enforcement to stop illegal hunting and illegal forest destruction is absolutely key. Long-term success can only be achieved by focusing local and global public awareness, and actively engaging with international organizations, multinational businesses and consumer nations to reduce unsustainable demands on the environment. Finally, the four primate range countries need to ensure that integrated, sustainable land-use planning for economic development includes the maintenance of biodiversity and intact, functional natural ecosystems.

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Primates in peril: the significance of Brazil, Madagascar, Indonesia and the Democratic Republic of the Congo for global primate conservation

Background 
Facilities across Africa care for apes orphaned by the trade for “bushmeat.” These facilities, called sanctuaries, provide housing for apes such as bonobos (Pan paniscus) and chimpanzees (Pan troglodytes) who have been illegally taken from the wild and sold as pets. Although these circumstances are undoubtedly stressful for the apes, most individuals arrive at the sanctuaries as infants and are subsequently provided with rich physical and social environments that can facilitate the expression of species-typical behaviors.


Methods and Findings 
We tested whether bonobo and chimpanzee orphans living in sanctuaries show any behavioral, physiological, or cognitive abnormalities relative to other individuals in captivity as a result of the early-life stress they experience. Orphans showed lower levels of aberrant behaviors, similar levels of average cortisol, and highly similar performances on a broad battery of cognitive tests in comparisons with individuals of the same species who were either living at a zoo or were reared by their mothers at the sanctuaries.


Conclusion 
Taken together, these results support the rehabilitation strategy used by sanctuaries in the Pan-African Sanctuary Alliance (PASA) and suggest that the orphans we examined did not show long-term signs of stress as a result of their capture. Our findings also show that sanctuary apes are as psychologically healthy as apes in other captive settings and thus represent a valuable resource for non-invasive research.

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Psychological Health of Orphan Bonobos and Chimpanzees in African Sanctuaries

‘Contest hoots’ are acoustically complex vocalisations produced by adult and subadult male bonobos (Pan paniscus). These calls are often directed at specific individuals and regularly combined with gestures and other body signals. The aim of our study was to describe the multi-modal use of this call type and to clarify its communicative and social function. To this end, we observed two large groups of bonobos, which generated a sample of 585 communicative interactions initiated by 10 different males. We found that contest hooting, with or without other associated signals, was produced to challenge and provoke a social reaction in the targeted individual, usually agonistic chase. Interestingly, ‘contest hoots’ were sometimes also used during friendly play. In both contexts, males were highly selective in whom they targeted by preferentially choosing individuals of equal or higher social rank, suggesting that the calls functioned to assert social status. Multi-modal sequences were not more successful in eliciting reactions than contest hoots given alone, but we found a significant difference in the choice of associated gestures between playful and agonistic contexts. During friendly play, contest hoots were significantly more often combined with soft than rough gestures compared to agonistic challenges, while the calls' acoustic structure remained the same. We conclude that contest hoots indicate the signaller's intention to interact socially with important group members, while the gestures provide additional cues concerning the nature of the desired interaction.

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Multi-modal use of a socially directed call in bonobos.

With the number of threatened species in rescue centres rising, scientific reports on the functioning and success of such centres is essential. Compassionate conservation tries to bridge the gap between animal welfare advocates and conservation biologists, recognising the benefits of preserving a species and its individuals. A case in point is that of Indonesia's threat- ened slow lorises Nycticebus spp., where illegal trade is decimating wild populations of these pri- mates. We present 4 yr of data from Ciapus Primate Centre in Indonesia, which received 180 slow lorises between 2008 and 2011. We show that >85% of these primates were unsuitable for reintro- duction; 23 slow lorises that were deemed suitable for reintroduction were released to the wild between 2010 and 2013 and were followed with radio tracking. Eleven of them died (on average 76 d post-release), 1 was recaptured (148 d post-release), 6 are no longer being monitored (after, on average, 263 d post-release) and their status is unknown, and 5 are still being monitored (aver- age 226 d post-release, as of December 2013). The challenges posed by work with slow lorises in the Ciapus Primate Centre over these 4 yr, with release success highly variable, show that even with concerted effort, rescue centres need to consider alternative options. We review such options, considering the pros and cons of euthanasia, life in captivity and reintroduction to the wild. We conclude that in today's global conservation crisis, it can only be beneficial to combine the expert- ise of animal welfare practitioners and conservation biologists.

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Compassionate conservation, rehabilitation and translocation of Indonesian slow lorises

Have you been to a football game lately? Think of the last time you were in an arena that seated fifty or even a hundred thousand people. That many people can make a lot of noise, but of course only represent a tiny piece of humanity today. If we could convince all the bonobos in the world to attend such a game, you could not come close to filling even the smallest professional football stadium. Our closest living relative is slipping off the precipice; their extinction in our own lifetime is a real possibility. The best estimates of the current bonobo population in the wild are somewhere between 5,000–50,000 individuals; all live in the Democratic Republic of Congo (DRC), the only country in which they are found indigenously (Teleki and Baldwin 1979, Kano 1984, Van Krunkelsven 2001). While it might seem an administrative blessing to have bonobos concentrated in one single large country, this rare species still shares all the problems of population fragmentation, habitat loss, and victimization due to the bushmeat trade practice by their African cousins. In addition, by being concentrated in one country, this species’ survival is dependent upon the state of one single nation – for better or worse. The ubiquitous threats to African apes seem particularly acute in the case of the bonobo as a result of DRC’s ill fortune during the past decade. However, the DRC has begun recovering from a decade of wars and now has the chance to jump from an impoverished victim of an oft forgotten war between seven nations, to a regional power as it struggles to redevelop its shattered economy through what to many must seem like an infinite supply of natural resources (Clark 2002). What will the

The Conservation Value of Lola ya Bonobo Sanctuary

Poaching and habitat destruction in the Congo Basin threaten African great apes including the bonobo (Pan paniscus), chimpanzees (Pan troglodytes), and gorillas (Gorilla spp.) with extinction. One way to combat extinction is to reintroduce rescued and rehabilitated apes and repopulate native habitats. Reintroduction programs are only successful if they are supported by local populations. Ekolo ya Bonobo, located in Equateur province of the Democratic Republic of Congo (DRC), is the world's only reintroduction site for rehabilitated bonobos. Here we assess whether children, of the Ilonga-Poo, living adjacent to Ekolo ya Bonobo demonstrate more pro-ape conservation attitudes than children living in, Kinshasa, the capital city. We examined children's attitudes toward great apes because children are typically the focus of conservation education programs. We used the Great Ape Attitude Questionnaire to test the Contact Hypothesis, which posits that proximity to great ape habitat influences pro-conservation attitudes toward great apes. Ilonga-Poo children who live in closer contact with wild bonobos felt greater responsibility to protect great apes compared to those in Kinshasa who live outside the natural habitat of great apes. These results suggest that among participants in the DRC, spatial proximity to a species fosters a greater sense of responsibility to protect and conserve. These results have implications for the successful implementation of great ape reintroduction programs in the Congo Basin. The data analyzed in this study were collected in 2010 and therefore provide a baseline for longitudinal study of this reintroduction site.

Dominique Morel

Papers

The Conservation Value of Lola ya Bonobo Sanctuary

Assessing conservation attitudes and behaviors of Congolese children neighboring the world's first bonobo (Pan paniscus) release site.